My first project, learning C!

main.cpp

//what commands to include (header)
#include <iostream>
//using standard library
using namespace std;
//function main, returns intiger
int main()
//start program
{
    //C Out \n=new line
    cout << "Hello world!\n";
    //Reads imput4, expects return key
    int number;
    cout << "Enter a Number,0-9\n" ;
    cin>> number;
    cin.ignore();
    if ( number==0 ) {
    cout<<"0 is a valid input :D\n";
    }
    if ( number==1 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==2 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==3 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==4 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==5 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==6 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==7 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==8 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number==9 ){
    cout<< number << " is a valid input :D\n";
    }
    if ( number-272==1 ) {
    cout<< "You got the secret code!\n";
    goto A;
    }
    if ( number>9 ) {
    cout<< "Not a valid imput\n";
    }
    if ( number<0 ) {
    cout<< "Not a valid imput\n";
    }
    A:
    cin.get();
    //outputs code one after program run

    return number ;

}